package com.fishercoder.solutions;

import java.util.ArrayList;
import java.util.List;

/**
 * 89. Gray Code
 *
 * The gray code is a binary numeral system where two successive values differ in only one bit.
 * Given a non-negative integer n representing the total number of bits in the code,
 * print the sequence of gray code.
 * A gray code sequence must begin with 0.

 For example, given n = 2, return [0,1,3,2]. Its gray code sequence is:

 00 - 0
 01 - 1
 11 - 3
 10 - 2

 Note:

 For a given n, a gray code sequence is not uniquely defined.

 For example, [0,2,3,1] is also a valid gray code sequence according to the above definition.

 For now, the judge is able to judge based on one instance of gray code sequence. Sorry about that.
 */

public class _89 {

  public static class Solution1 {
    public List<Integer> grayCode(int n) {
      List<Integer> result = new ArrayList();
      for (int i = 0; i < (1 << n); i++) {
        result.add(i ^ (i >> 1));
      }
      return result;
    }
  }

}
